The present invention relates to an unloader suitable for stevedoring cargoes, especially bulk cargoes to be conveyed, from ships.
In a conventionally known unloader with a vertical screw conveyer, although the screw can swing in the direction parallel with the plane along which the boom is hoisted, it has been unable to swing in the direction perpendicular to the plane and the boom.
However, in cases where cargoes of certain types or in certain conditions are involved, it is desired that the screw be capable of swinging also in the direction perpendicular to the boom, because this would be more convenient and more efficient in such cases.
In order to satisfy the above-stated requirement, an arrangement has been proposed in which the entire boom is adapted to tilt so as to enable the screw to swing in the direction perpendicular to the boom. However, this arrangement requires a complicated tilting mechanism, thereby causing an increase in equipment costs.